Persons using assistive technology might not be able to fully access information in this file. For assistance, please send e-mail to: mmwrq@cdc.gov. Type 508 Accommodation and the title of the report in the subject line of e-mail.

During January 1--October 7, 2006, a total of 45 states* and the District of Columbia reported 5,783 confirmed
or probable mumps cases to CDC (Figure). This includes 2,597 cases previously reported by 11 states during January
1--April 29, 2006 (1). This report summarizes the epidemiology of mumps cases in the United States during 2006. With low levels
of reported mumps continuing, health-care workers should remain alert to suspected mumps, conduct appropriate
laboratory testing, and use every opportunity to ensure adequate immunity, particularly among populations at high risk for mumps.

Cases of mumps are reportable through the National Notifiable Diseases Surveillance System (NNDSS). Reports
are transmitted electronically via NNDSS to CDC each week and include individual case information such as age, sex, date
of symptom onset, vaccination status, and complications of illness. Mumps cases included in this report are those
with onset from January 1 (week 1) through October 7, 2006
(week 40).

The clinical case definition of mumps is an illness with acute onset of unilateral or bilateral tender, self-limited, swelling
of the parotid or other salivary gland, lasting 2 or more days, and without other apparent cause. A confirmed case of mumps
is one that is laboratory confirmed or meets the clinical case definition and is linked epidemiologically to a confirmed
or probable case. A probable case meets the clinical case definition but is neither laboratory confirmed nor linked
to another confirmed or probable mumps case
(2).

Of the 5,783 cases, 3,113 (54%) were confirmed, and 2,612 (45%) were probable; for 58 cases (1%), classification
was unknown. Six states reported 84% of the cases: Iowa (1,968), Kansas (904), Wisconsin (750), Illinois (591), Nebraska
(357), and South Dakota (288).

For 5,747 (99%) of the 5,783 mumps cases with patient age available, the median age was 22 years (range: 1
month--96 years). Among the 5,739 (99%) patients for whom sex was known, 3,644 (63%) were female. As reported previously
(1), the highest age-specific rate continues to be among persons aged 18--24 years, many of whom were college students.

Data regarding vaccination status are incomplete. In Iowa, one of the states with the most complete data,
preliminary vaccination data have been reported through September 30. Among 1,798 patients with completed follow-up reports,
123 (7%) were unvaccinated; 245 (14%) had received 1 dose of measles, mumps, and rubella (MMR) vaccine, and 884 (49%)
had received >2 doses of MMR vaccine. The vaccination status of 546 (30%) patients, the majority of whom were adults,
was unknown (3).

Among the 5,783 cases for which weeks of onset are known, cases peaked during April 16--29, the onset period for
1,498 (26%) cases (Figure). The number of reported cases decreased during May--September, when most students were
not attending college. However, since students began returning to school in August, mumps clusters have been reported from
three college or university campuses in Illinois (84 cases), Kansas (22 cases), and Virginia (12 cases). Most of these cases (96%)
were reported in persons who had received 2 doses of MMR vaccine. Because 2 doses of mumps-containing vaccine are not
100% effective, in a setting with high vaccination coverage such as the United States, most mumps cases likely will occur in
persons who have received the 2 doses. Multiple other factors might have contributed to the spread of the mumps outbreak (e.g.,
the close-contact environment of college dormitories or varying college admission requirements for MMR vaccination)
(1).

Health-care providers should continue to remain alert for suspected mumps cases, conduct appropriate diagnostic
testing, and report these cases to local or state health departments. At the initial visit, recommended specimens for laboratory
testing include serum to test for mumps immunoglobulin M (IgM) antibodies and a swab from the parotid duct or other
affected salivary gland ducts for viral isolation, reverse transcriptase--polymerase chain reaction testing, or both. Parotid duct swab
is the preferred viral sample for mumps; urine samples are no longer recommended. The first (acute) serum specimen should
be collected within 5 days of illness onset. If the IgM antibody titer is negative, a second (convalescent) serum specimen for
IgM antibodies is recommended 2--3 weeks after onset of signs (e.g., parotitis) or symptoms; a
delayed IgM response has been observed in patients with confirmed cases of mumps, especially in vaccinated persons. The paired serum specimens also can
be used to detect a significant rise (as defined by the testing kit instructions) in immunoglobulin G (IgG seroconversion)
if measured by enzyme-linked immunosorbent assay or a fourfold rise in
titer if measured using plaque-reduction
neutralization assays or similar quantitative assay. Negative laboratory tests, especially in vaccinated persons, should not be used to rule out
a mumps diagnosis, because these tests are not sensitive enough to
detect infection in all persons with clinical illness. In
the absence of another diagnosis, cases meeting the clinical case definition should be reported as mumps cases.

In response to this nationwide mumps outbreak, ACIP recommendations for prevention and control of mumps
were updated (4). Evidence of immunity through documentation of vaccination is now defined as 1 dose of live mumps vaccine
for preschool-aged children and adults not at high risk for exposure and infection and 2 doses of live mumps vaccine for
school-aged children (i.e., grades kindergarten--12) and adults at high risk for exposure and infection (i.e., health-care
workers, international travelers, and students at post--high-school education institutions). Additional recommendations for
outbreak control include administering a second dose of MMR for preschool children and adults not at high risk for exposure
and infection if these persons are part of a group that is experiencing an outbreak
(4). To ensure high levels of immunity,
especially among groups at high risk for exposure and infection, every opportunity should be used to provide the first or second dose
of MMR vaccine to those without adequate evidence of immunity (e.g., documentation of vaccination). Private
health-care providers, clinics, health departments, health-care institutions, schools, universities, and colleges should consider
offering MMR vaccine through such settings as routine preventive health services and special immunization clinics,
including providing MMR in conjunction with influenza
vaccine.

Use of trade names and commercial sources is for identification only and does not imply endorsement by the U.S. Department of
Health and Human Services.References to non-CDC sites on the Internet are
provided as a service to MMWR readers and do not constitute or imply
endorsement of these organizations or their programs by CDC or the U.S.
Department of Health and Human Services. CDC is not responsible for the content
of pages found at these sites. URL addresses listed in MMWR were current as of
the date of publication.

DisclaimerAll MMWR HTML versions of articles are electronic conversions from ASCII text
into HTML. This conversion may have resulted in character translation or format errors in the HTML version.
Users should not rely on this HTML document, but are referred to the electronic PDF version and/or
the original MMWR paper copy for the official text, figures, and tables.
An original paper copy of this issue can be obtained from the Superintendent of Documents,
U.S. Government Printing Office (GPO), Washington, DC 20402-9371; telephone: (202) 512-1800.
Contact GPO for current prices.

**Questions or messages regarding errors in formatting should be addressed to
mmwrq@cdc.gov.